The effect of material contact and adhesion proteins on induction of the procoagulant state in platelets is being investigated. The substrates used are Immulon I, untreated 96-well microtiter plates and C3F6 RFGD plasma-coated Immulon I plates. Surfaces are preadsorbed with normal or depleted (missing Fg, Fn, or both) plasma and then exposed to the platelet-containing solution. Adherent platelets are incubated with a mixture of Va, Xa, and prothrombin in PSB. Thrombin generation is stopped at the time points of the study by the addition of EDTA. ESCA is used to characterize the composition and chemistry of the substrates.